Hydrofoils are wings that are adapted to function in water as opposed to air, but share many similar attributes. Notably, a hydrofoil provides a significant amount of lift, even at relatively slow speeds. Accordingly, the benefits of a hydrofoil may be extended to any number of applications involving movement through the water. For example, nearly any recreational pursuit that involves riding a board may take advantage of a hydrofoil, including kitesurfing, wind surfing, stand up paddle boarding, wake boarding, water skiing, tow-in surfing, conventional surfing and others.
An important characteristic associated with a hydrofoil-equipped craft is the concept of a threshold speed. Below this speed, the hydrofoil is unable to generate the lift necessary to suspend the hull of the craft, such as a surfboard, above the water. Consequently, in addition to whatever friction is attributed to the hydrofoil, the hull displaces water and presents a significant amount of surface area to the water. Both aspects dramatically increase the drag experienced by the craft. However, above the threshold speed, the hydrofoil generates sufficient force to lift the hull of the craft free from the water surface, a condition typically termed “flying.” This takes all drag components associated with the hull out of the equation, leaving only the hydrofoil friction, which is relatively unchanged. Due to the significant reduction in drag, much less force is required to keep the craft at or above the threshold speed than may be required to accelerate the craft to the threshold speed. This phenomenon is similar to the transition of a hull from a displacement mode to a planning mode, when a reduced surface area of the hull is able to “skip” across the water. While readily appreciated in any number of sports, it is magnified here given the greater efficiency of the hydrofoil. The techniques of this disclosure facilitate attaining the threshold speed as will be appreciated in view of the following discussion.